Quantum wells are solid state electronic devices that are well known in the art. Among other things, quantum wells can be used to form light emitting diodes (LEDs), semiconductor lasers, and other tunneling devices. An representative example of a quantum well structure is depicted in FIG. 7. In FIG. 7, a quantum well structure 700 is depicted as comprising a substrate 705 and a plurality of alternating layers 710, (X and Y). Each of these alternating layers, X and Y, comprises a different composition of semiconductor material, thereby creating alternating band-gap diagrams. Although the quantum well structure 700 in FIG. 7 is depicted as comprising multiple layers, it is well known in the art that a quantum well structure may be comprised of a several hundred layers, or only one alternating layer, forming a single quantum well. Although it is usually preferable to use as many quantum wells in a quantum well layer as possible, the cost of fabrication can limit the number of quantum well that can be economically incorporated into the device. The thickness and composition of the alternating layers in a quantum well structure can be varied to produce a variety of other effects. A representative depiction of the alternating band-gap diagrams created by the alternating semiconductor layers 710 is illustrated in FIG. 8.
In FIG. 8, the band gap for each of the layers alternates between a large band gap E1, which corresponds to the band gap of material X, and a smaller band gap E2, which corresponds to the band gap of material Y. The juxtaposition of these two layers at very small dimensions causes the distance between the conduction band Fermi level and the valence band Fermi level in material Y to be widened from energy level E2 to energy level E3. This widening allows the quantum well to perform as if it were operating as a different kind of material with a wider band-gap. Accordingly, when properly pumped and stimulated, quantum well devices can emit light at wavelengths that would not normally be associated with typical semiconductor materials. These devices can therefore provide great utility for a wide variety electronic devices.
One problem associated with existing quantum well structures relates to how the quantum well is energized (i.e. pumped). Existing methods for energizing a quantum include applying an electric field across the quantum well, optically pumping the well with photons of sufficient energy (i.e. wavelength), and thermally pumping the well with a heat source and a cold sink to induce a population inversion. These methods are undesirable because they require a step of converting primary energy into an intermediate energy source, such as optical energy, electrical energy, or thermal energy. There is therefore a need in the art for a method and apparatus for directly energizing a quantum well with a primary energy source. By directly energizing a quantum well with a primary energy source, the intermediate step of energy conversion can be eliminated, thus reducing the complexity of the system and improving its efficiency.